With a ubiquitous advertising campaign, some gruesome green graphics and more than a hint of a smirk, the man Tony Blair allegedly described as "a slug", Piers Morgan, made his debut on CNN as the network's new lead interviewer.

"There's going to be a learning curve for you," his first interviewee, Oprah Winfrey, warned him during the show. "Should we judge you and say that you're no good just because you've made all these mistakes?"

"If you do that to me I'm going to be mortified," replied Morgan, going visibly pale.

And understandably so. To British viewers, Morgan seems like the protagonist from a satirical novel about the modern day media. Not even Henry Fielding would have dreamed of a character, brought so high, then so low, then so insanely high again, all by his own hubris. If there is a moral to the story of Morgan, it's to never doubt yourself, no matter how many others do.

And always plug Simon Cowell's bands in your tabloid so that when you eventually get fired one day, he'll offer you a job.

But to Americans, he is a lesser known quantity and this is his chance to convince them that his appointment as the successor to Larry King is not the wackiest choice since John McCain selected an unknown Alaskan governor named Sarah Palin as his vice-presidential running mate.

Americans know Morgan solely as the judge on America's Got Talent and the winner of Celebrity Apprentice. Yet Morgan hasn't been able to point them to his 20-year record as a journalist in Britain because of those pesky share tipping and faked photo stories.

And so, Morgan – never known for his light touch – defused the problem by getting Winfrey herself to establish his credentials in the opening few minutes of the show. "They tell me Piers Morgan is a great interviewer," murmured Winfrey when the camera just happened to be upon her. "Let's see how good he is."

All month CNN – which is hoping Morgan will bring a bit of spark to the bland news network – has been trailing Winfrey telling Morgan, "You're good." But on the show, this turned out to be Winfrey's response to Morgan's question about her wealth, and she avoided giving any actual figures. But he did get some good personal details out of the notoriously private Winfrey, such as when she found out she was pregnant at the age of 14.

"I thought, I'm going to have to kill myself," she said. Did she try? "No," she insisted, before adding, "I did crazy things like drinking detergent and all that kinda crazy stuff that you do when you're trying to get attention."

While he may not have been wearing Larry King's red braces, or sitting in King's studio (instead, it was filmed in a cluttered hotel room with an unfortunate, strange horse statue behind Morgan on which the rider appeared to be about to plunge a spear into his skull) he didn't entirely do away with all of his predecessor's trappings. There was a definite lick of subservience to Winfrey that was wholly lacking from, say, Morgan's interview with Katie Price on ITV.

Whether Morgan's chummy interviews will rescue CNN remains to be seen. But he's probably the most interesting thing on that channel. And knowing Morgan, he'll take that as a compliment.